Exact Diagonalization Approach for Atomistic Calculation of Piezoelectric Effects in Semiconductor Quantum Dots

Świderski, M.; Zieliński, Michał

doi:10.12693/aphyspola.129.a-79

Cited by 6 publications

(3 citation statements)

References 30 publications

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“…The brightest lines, which form avoided crossings, are well reproduced by the simulation. In order to relate the spectra to the morphological characteristics of the QDM and to confirm the form of the spectrum with a model based on realistic wave functions and an extended number of hole and trion states, we have performed k · p calculations − of the trion PL spectra. In spite of the multiple transitions present in the k · p model, the low-excitation PL spectrum is very similar to that obtained in the semiempirical model (SI).…”

Section: Resultsmentioning

confidence: 99%

Controlled Coherent Coupling in a Quantum Dot Molecule Revealed by Ultrafast Four-Wave Mixing Spectroscopy

et al. 2023

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Semiconductor quantum dot molecules are considered promising candidates for quantum technological applications due to their wide tunability of optical properties and coverage of different energy scales associated with charge and spin physics. While previous works have studied the tunnel-coupling of the different excitonic charge complexes shared by the two quantum dots by conventional optical spectroscopy, we here report on the first demonstration of a coherently controlled interdot tunnel-coupling focusing on the quantum coherence of the optically active trion transitions. We employ ultrafast four-wave mixing spectroscopy to resonantly generate a quantum coherence in one trion complex, transfer it to and probe it in another trion configuration. With the help of theoretical modeling on different levels of complexity, we give an instructive explanation of the underlying coupling mechanism and dynamical processes.

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Section: Resultsmentioning

confidence: 99%

Controlled Coherent Coupling in a Quantum Dot Molecule Revealed by Ultrafast Four-Wave Mixing Spectroscopy

et al. 2023

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“…Minimization of strain energy is performed with the conjugate gradient method. [53,54] Next, the piezoelectric potential [55][56][57][58][59][60] is calculated by accounting for both linear and quadratic contributions, with piezoelectric coefficients from Ref. [57].…”

Section: Systems and Methodsmentioning

confidence: 99%

Dark-bright excitons mixing in alloyed InGaAs self-assembled quantum dots

Zieliński

2021

Preprint

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Quantum dots are arguably one of the best platforms for optically accessible spin based qubits. The paramount demand of extended qubit storage time can be met by using quantum-dot-confined dark exciton: a longlived electron-hole pair with parallel spins. Despite its name the dark exciton reveals weak luminescence that can be directly measured. The origins of this optical activity remain largely unexplored. In this work, using the atomistic tight-binding method combined with configuration-interaction approach, we demonstrate that atomic-scale randomness strongly affects oscillator strength of dark excitons confined in self-assembled cylindrical InGaAs quantum dots with no need for faceting or shape-elongation. We show that this process is mediated by two mechanisms: mixing dark and bright configurations by exchange interaction, and equally important appearance of non-vanishing optical transition matrix elements that otherwise correspond to nominally forbidden transitions in a non-alloyed case. The alloy randomness has essential impact on both bright and dark exciton states, including their energy, emission intensity, and polarization angle. We conclude that, due to the atomic-scale alloy randomness, finding dots with desired dark exciton properties may require exploration of a large ensemble, similarly to how dots with low bright exciton splitting are selected for entanglement generation.

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“…Having the single-particle states we then compute the exciton states which are found using the configuration interaction (CI) method. The axial field is included at the CI stage 26 . Due to numerical efficiency reasons we limit our basis to 4 lowest electron and hole states (i.e.…”

Section: A Carrier System and Its Modelmentioning

confidence: 99%

Polaron resonances in two vertically stacked quantum dots

Karwat¹,

Gawarecki²,

Machnikowski³

2017

Phys. Rev. B

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In this work, we present a theoretical study of polaron states in a double quantum dot system. We present realistic calculations which combine 8 band k·p model, configuration interaction approach and collective modes method. We investigate the dependence of polaron energy branches on axial electric field. We show that coupling between carriers and longitudinal optical phonons via Fröhlich interaction leads to qualitative and quantitative reconstruction of the optical spectra. In particular, we study the structure of resonances between the states localized in different dots. We show that p-shell states are strongly coupled to the phonon replicas of s-shell states, in contrast to the weak direct s-p coupling. We discuss also the dependence of the phonon-assisted tunnel coupling strength on the separation between the dots.

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Exact Diagonalization Approach for Atomistic Calculation of Piezoelectric Effects in Semiconductor Quantum Dots

Cited by 6 publications

References 30 publications

Controlled Coherent Coupling in a Quantum Dot Molecule Revealed by Ultrafast Four-Wave Mixing Spectroscopy

Controlled Coherent Coupling in a Quantum Dot Molecule Revealed by Ultrafast Four-Wave Mixing Spectroscopy

Dark-bright excitons mixing in alloyed InGaAs self-assembled quantum dots

Polaron resonances in two vertically stacked quantum dots

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